Does any one know what the green slimy stuff in the growbeds and in the pipes is all about? is it algae? is it good or bad for the systems, fish, plants? Do I need to get rid of it? more of it?
Yes it is likely algae and no it is not "bad" other than it is an unwanted plant taking up nutrients. To address it you need to keep the top 1-2 inches of your grow bed dry. Algae also requires light so simply shading your pipes will get rid of it there.
They may nibble on it but in aquaponics you should be relying of fish food as the base of your nutrients. There are other species that are better algae eaters.